Keith Smith
720 lines
26 KiB
Python
720 lines
26 KiB
Python
from dataclasses import dataclass, field
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import random
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import re
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import socket
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from typing import Any
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class SnmpDiscoveryError(Exception):
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pass
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@dataclass(frozen=True)
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class SnmpCredential:
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community: str
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port: int = 161
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timeout_seconds: int = 5
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retries: int = 1
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@dataclass(frozen=True)
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class DiscoveredSnmpInterface:
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index: int
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name: str
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label: str
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description: str | None
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admin_status: str | None
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oper_status: str | None
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speed_bps: int | None
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@dataclass(frozen=True)
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class DiscoveredSnmpHealthItem:
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item_id: str
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item_type: str
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group: str
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label: str
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unit: str | None = None
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@dataclass(frozen=True)
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class DiscoveredSnmpDevice:
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host: str
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device_name: str | None
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description: str | None
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uptime_seconds: int | None
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interfaces: list[DiscoveredSnmpInterface]
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profile_key: str = "generic_snmp"
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profile_name: str = "Generic SNMP"
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capabilities: dict[str, bool] = field(default_factory=dict)
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health_items: list[DiscoveredSnmpHealthItem] = field(default_factory=list)
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@dataclass(frozen=True)
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class InterfaceIdentity:
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label: str
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name: str
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description: str | None
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SYS_DESCR = (1, 3, 6, 1, 2, 1, 1, 1, 0)
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SYS_UPTIME = (1, 3, 6, 1, 2, 1, 1, 3, 0)
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SYS_NAME = (1, 3, 6, 1, 2, 1, 1, 5, 0)
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IF_DESCR = (1, 3, 6, 1, 2, 1, 2, 2, 1, 2)
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IF_SPEED = (1, 3, 6, 1, 2, 1, 2, 2, 1, 5)
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IF_ADMIN_STATUS = (1, 3, 6, 1, 2, 1, 2, 2, 1, 7)
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IF_OPER_STATUS = (1, 3, 6, 1, 2, 1, 2, 2, 1, 8)
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IF_NAME = (1, 3, 6, 1, 2, 1, 31, 1, 1, 1, 1)
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HR_PROCESSOR_LOAD = (1, 3, 6, 1, 2, 1, 25, 3, 3, 1, 2)
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HR_STORAGE_TYPE = (1, 3, 6, 1, 2, 1, 25, 2, 3, 1, 2)
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HR_STORAGE_DESCR = (1, 3, 6, 1, 2, 1, 25, 2, 3, 1, 3)
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HR_STORAGE_ALLOCATION_UNITS = (1, 3, 6, 1, 2, 1, 25, 2, 3, 1, 4)
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HR_STORAGE_SIZE = (1, 3, 6, 1, 2, 1, 25, 2, 3, 1, 5)
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HR_STORAGE_USED = (1, 3, 6, 1, 2, 1, 25, 2, 3, 1, 6)
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ENT_PHYSICAL_DESCR = (1, 3, 6, 1, 2, 1, 47, 1, 1, 1, 1, 2)
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ENT_PHYSICAL_NAME = (1, 3, 6, 1, 2, 1, 47, 1, 1, 1, 1, 7)
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ENT_PHY_SENSOR_TYPE = (1, 3, 6, 1, 2, 1, 99, 1, 1, 1, 1)
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ENT_PHY_SENSOR_SCALE = (1, 3, 6, 1, 2, 1, 99, 1, 1, 1, 2)
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ENT_PHY_SENSOR_PRECISION = (1, 3, 6, 1, 2, 1, 99, 1, 1, 1, 3)
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ENT_PHY_SENSOR_VALUE = (1, 3, 6, 1, 2, 1, 99, 1, 1, 1, 4)
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ENT_PHY_SENSOR_OPER_STATUS = (1, 3, 6, 1, 2, 1, 99, 1, 1, 1, 5)
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UCD_LA_LOAD_INT = (1, 3, 6, 1, 4, 1, 2021, 10, 1, 5)
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UCD_MEM_TOTAL_REAL = (1, 3, 6, 1, 4, 1, 2021, 4, 5, 0)
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UCD_MEM_AVAIL_REAL = (1, 3, 6, 1, 4, 1, 2021, 4, 6, 0)
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UCD_DSK_PATH = (1, 3, 6, 1, 4, 1, 2021, 9, 1, 2)
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UCD_DSK_PERCENT = (1, 3, 6, 1, 4, 1, 2021, 9, 1, 9)
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HR_STORAGE_RAM = "1.3.6.1.2.1.25.2.1.2"
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HR_STORAGE_VIRTUAL_MEMORY = "1.3.6.1.2.1.25.2.1.3"
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HR_STORAGE_FIXED_DISK = "1.3.6.1.2.1.25.2.1.4"
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HR_STORAGE_REMOVABLE_DISK = "1.3.6.1.2.1.25.2.1.5"
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STATUS_LABELS = {
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1: "up",
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2: "down",
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3: "testing",
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4: "unknown",
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5: "dormant",
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6: "not present",
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7: "lower layer down",
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}
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SENSOR_TYPE_LABELS = {
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3: ("AC voltage", "V"),
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4: ("DC voltage", "V"),
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5: ("Current", "A"),
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6: ("Power", "W"),
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7: ("Frequency", "Hz"),
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8: ("Temperature", "C"),
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9: ("Humidity", "%"),
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10: ("Fan speed", "rpm"),
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11: ("Airflow", "m3/min"),
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12: ("Sensor state", None),
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}
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@dataclass(frozen=True)
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class SnmpProfile:
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key: str
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name: str
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match_terms: tuple[str, ...] = ()
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health_source: str = "standard"
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include_interfaces: bool = True
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def matches(self, system_text: str) -> bool:
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return any(term in system_text for term in self.match_terms)
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def discover_health_items(self, client: "SnmpV2Client") -> list[DiscoveredSnmpHealthItem]:
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if self.health_source == "linux":
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linux_items = _discover_linux_server_items(client)
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host_items = _discover_host_resource_items(client)
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if any(item.item_type == "linux_memory_usage" for item in linux_items):
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host_items = [item for item in host_items if item.item_type != "memory_usage"]
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return _deduplicate_items([*linux_items, *host_items, *_discover_sensor_items(client)])
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return [*_discover_host_resource_items(client), *_discover_sensor_items(client)]
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SNMP_PROFILES = (
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SnmpProfile("cisco_ios", "Cisco IOS SNMP", ("cisco", "ios")),
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SnmpProfile("mikrotik_routeros", "MikroTik RouterOS SNMP", ("mikrotik", "routeros")),
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SnmpProfile("proxmox_ve", "Proxmox VE Server", ("proxmox", "-pve", " pve "), health_source="linux"),
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SnmpProfile("linux_server", "Linux Server", ("linux", "net-snmp"), health_source="linux"),
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SnmpProfile("generic_snmp", "Generic SNMP"),
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)
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def discover_snmp_device(host: str, credential: SnmpCredential, asset_type: str | None = None) -> DiscoveredSnmpDevice:
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client = SnmpV2Client(host, credential)
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system = client.get_many([SYS_NAME, SYS_DESCR, SYS_UPTIME])
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profile = _select_profile(system, asset_type)
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interfaces = _discover_interfaces(client) if profile.include_interfaces else []
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health_items = profile.discover_health_items(client)
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return DiscoveredSnmpDevice(
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host=host,
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device_name=_string_value(system.get(SYS_NAME)),
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description=_string_value(system.get(SYS_DESCR)),
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uptime_seconds=_timeticks_to_seconds(system.get(SYS_UPTIME)),
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interfaces=interfaces,
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profile_key=profile.key,
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profile_name=profile.name,
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capabilities=_capabilities(system, interfaces, health_items),
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health_items=health_items,
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)
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def _select_profile(system: dict[tuple[int, ...], Any], asset_type: str | None = None) -> SnmpProfile:
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system_text = " ".join(
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value.lower()
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for value in [_string_value(system.get(SYS_NAME)), _string_value(system.get(SYS_DESCR))]
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if value
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)
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normalized_asset_type = (asset_type or "").strip().lower()
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if normalized_asset_type == "server":
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proxmox_profile = _profile_by_key("proxmox_ve")
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if proxmox_profile.matches(system_text):
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return proxmox_profile
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return _profile_by_key("linux_server")
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if normalized_asset_type == "network_device":
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for profile in SNMP_PROFILES:
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if profile.include_interfaces and profile.match_terms and profile.matches(system_text):
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return profile
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return _profile_by_key("generic_snmp")
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for profile in SNMP_PROFILES:
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if profile.match_terms and profile.matches(system_text):
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return profile
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return SNMP_PROFILES[-1]
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def _profile_by_key(key: str) -> SnmpProfile:
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for profile in SNMP_PROFILES:
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if profile.key == key:
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return profile
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raise KeyError(key)
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def _capabilities(
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system: dict[tuple[int, ...], Any],
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interfaces: list[DiscoveredSnmpInterface],
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health_items: list[DiscoveredSnmpHealthItem],
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) -> dict[str, bool]:
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item_types = {item.item_type for item in health_items}
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return {
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"system": any(system.get(oid) is not None for oid in [SYS_NAME, SYS_DESCR, SYS_UPTIME]),
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"interfaces": bool(interfaces),
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"interface_status": bool(interfaces),
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"interface_traffic": bool(interfaces),
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"interface_errors": bool(interfaces),
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"cpu": bool({"cpu_load", "linux_load_average"} & item_types),
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"memory": bool({"memory_usage", "linux_memory_usage"} & item_types),
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"storage": bool({"storage_usage", "linux_disk_usage"} & item_types),
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"sensors": "sensor_value" in item_types,
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"environmental": "sensor_value" in item_types,
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}
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def _discover_interfaces(client: "SnmpV2Client") -> list[DiscoveredSnmpInterface]:
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names = client.walk(IF_NAME)
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descriptions = client.walk(IF_DESCR)
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admin_statuses = client.walk(IF_ADMIN_STATUS)
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oper_statuses = client.walk(IF_OPER_STATUS)
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speeds = client.walk(IF_SPEED)
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indexes = sorted(
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{
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*_indexed_values(names).keys(),
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*_indexed_values(descriptions).keys(),
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*_indexed_values(admin_statuses).keys(),
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*_indexed_values(oper_statuses).keys(),
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*_indexed_values(speeds).keys(),
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}
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)
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name_by_index = _indexed_values(names)
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description_by_index = _indexed_values(descriptions)
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admin_by_index = _indexed_values(admin_statuses)
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oper_by_index = _indexed_values(oper_statuses)
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speed_by_index = _indexed_values(speeds)
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interfaces: list[DiscoveredSnmpInterface] = []
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for index in indexes:
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identity = _interface_identity(index, name_by_index.get(index), description_by_index.get(index))
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interfaces.append(
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DiscoveredSnmpInterface(
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index=index,
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name=identity.name,
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label=identity.label,
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description=identity.description,
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admin_status=_status_label(admin_by_index.get(index)),
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oper_status=_status_label(oper_by_index.get(index)),
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speed_bps=_int_value(speed_by_index.get(index)),
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)
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)
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return interfaces
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def _interface_identity(index: int, name_value: Any, description_value: Any) -> InterfaceIdentity:
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raw_name = _string_value(name_value)
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raw_description = _string_value(description_value)
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name = raw_name or raw_description or f"Interface {index}"
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description = raw_description if raw_description and raw_description != name else None
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return InterfaceIdentity(
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label=_friendly_interface_label(name, raw_description, index),
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name=name,
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description=description,
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)
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def _friendly_interface_label(name: str, description: str | None, index: int) -> str:
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value = _clean_interface_text(name) or _clean_interface_text(description or "") or f"Interface {index}"
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lower = value.lower()
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if lower in {"lo", "lo0", "loopback", "loopback0"}:
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return "Loopback"
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if lower.startswith("vlan"):
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suffix = _suffix_after_prefix(value, "vlan")
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return f"VLAN {suffix}" if suffix else "VLAN"
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if lower.startswith("bridge"):
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suffix = _suffix_after_prefix(value, "bridge")
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return f"Bridge {suffix}" if suffix else "Bridge"
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if lower.startswith("br-"):
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return f"Bridge {value[3:]}"
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if lower.startswith("bond"):
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suffix = _suffix_after_prefix(value, "bond")
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return f"Bond {suffix}" if suffix else "Bond"
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if lower.startswith("lag"):
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suffix = _suffix_after_prefix(value, "lag")
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return f"LAG {suffix}" if suffix else "LAG"
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if lower.startswith("sfp-sfpplus"):
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suffix = _suffix_after_prefix(value, "sfp-sfpplus")
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return f"SFP+ {suffix}" if suffix else "SFP+"
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if lower.startswith("sfpplus"):
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suffix = _suffix_after_prefix(value, "sfpplus")
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return f"SFP+ {suffix}" if suffix else "SFP+"
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if lower.startswith("sfp"):
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suffix = _suffix_after_prefix(value, "sfp")
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return f"SFP {suffix}" if suffix else "SFP"
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if lower.startswith("ethernet"):
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suffix = _suffix_after_prefix(value, "ethernet")
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return f"Ethernet {suffix}" if suffix else "Ethernet"
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if lower.startswith("ether"):
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suffix = _suffix_after_prefix(value, "ether")
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return f"Port {suffix}" if suffix else "Ethernet port"
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if lower.startswith("gi"):
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suffix = _suffix_after_prefix(value, "gi")
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return f"GigabitEthernet {suffix}" if suffix else "GigabitEthernet"
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if lower.startswith("te"):
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suffix = _suffix_after_prefix(value, "te")
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return f"TenGigabitEthernet {suffix}" if suffix else "TenGigabitEthernet"
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if lower.startswith("fa"):
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suffix = _suffix_after_prefix(value, "fa")
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return f"FastEthernet {suffix}" if suffix else "FastEthernet"
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if lower.startswith("ge-"):
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return f"GigabitEthernet {value[3:]}"
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if lower.startswith("xe-"):
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return f"TenGigabitEthernet {value[3:]}"
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if lower.startswith("et-"):
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return f"Ethernet {value[3:]}"
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return value
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def _clean_interface_text(value: str) -> str:
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cleaned = " ".join(value.strip().split())
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if not cleaned:
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return ""
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if cleaned.startswith("Interface "):
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return cleaned
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return cleaned
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def _suffix_after_prefix(value: str, prefix: str) -> str:
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suffix = value[len(prefix) :].strip(" -_./")
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return re.sub(r"\s+", " ", suffix)
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def _discover_host_resource_items(client: "SnmpV2Client") -> list[DiscoveredSnmpHealthItem]:
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items: list[DiscoveredSnmpHealthItem] = []
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processor_loads = _indexed_values(client.walk(HR_PROCESSOR_LOAD, max_items=256))
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processor_indexes = sorted(index for index, value in processor_loads.items() if _int_value(value) is not None)
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for position, index in enumerate(processor_indexes, start=1):
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label = "CPU load" if len(processor_indexes) == 1 else f"CPU {position} load"
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items.append(
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DiscoveredSnmpHealthItem(
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item_id=f"cpu.{index}.load",
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item_type="cpu_load",
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group="Device Health",
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label=label,
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unit="%",
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)
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)
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storage_types = _indexed_values(client.walk(HR_STORAGE_TYPE, max_items=256))
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descriptions = _indexed_values(client.walk(HR_STORAGE_DESCR, max_items=256))
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allocation_units = _indexed_values(client.walk(HR_STORAGE_ALLOCATION_UNITS, max_items=256))
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sizes = _indexed_values(client.walk(HR_STORAGE_SIZE, max_items=256))
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used = _indexed_values(client.walk(HR_STORAGE_USED, max_items=256))
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for index in sorted(storage_types):
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storage_type = _string_value(storage_types.get(index))
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allocation_unit = _int_value(allocation_units.get(index))
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size = _int_value(sizes.get(index))
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used_blocks = _int_value(used.get(index))
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if not storage_type or not allocation_unit or not size or used_blocks is None:
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continue
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description = _string_value(descriptions.get(index)) or f"Storage {index}"
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if storage_type in {HR_STORAGE_RAM, HR_STORAGE_VIRTUAL_MEMORY}:
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items.append(
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DiscoveredSnmpHealthItem(
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item_id=f"storage.{index}.memory",
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item_type="memory_usage",
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group="Device Health",
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label="Memory used",
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unit="%",
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)
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)
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elif storage_type in {HR_STORAGE_FIXED_DISK, HR_STORAGE_REMOVABLE_DISK}:
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if not _is_monitorable_storage_path(description):
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continue
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items.append(
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DiscoveredSnmpHealthItem(
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item_id=f"storage.{index}.usage",
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item_type="storage_usage",
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group="Storage",
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label=_storage_usage_label(description),
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unit="%",
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)
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)
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return _deduplicate_items(items)
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def _discover_linux_server_items(client: "SnmpV2Client") -> list[DiscoveredSnmpHealthItem]:
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items: list[DiscoveredSnmpHealthItem] = []
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load_values = _indexed_values(client.walk(UCD_LA_LOAD_INT, max_items=16))
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for index, label in [(1, "Load average 1 minute"), (2, "Load average 5 minutes"), (3, "Load average 15 minutes")]:
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if _int_value(load_values.get(index)) is not None:
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items.append(
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DiscoveredSnmpHealthItem(
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item_id=f"linux.load.{index}",
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item_type="linux_load_average",
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group="Server Health",
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label=label,
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)
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)
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memory = client.get_many([UCD_MEM_TOTAL_REAL, UCD_MEM_AVAIL_REAL])
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if _int_value(memory.get(UCD_MEM_TOTAL_REAL)) and _int_value(memory.get(UCD_MEM_AVAIL_REAL)) is not None:
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items.append(
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DiscoveredSnmpHealthItem(
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item_id="linux.memory.real",
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item_type="linux_memory_usage",
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group="Server Health",
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label="Memory used",
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unit="%",
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)
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)
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disk_paths = _indexed_values(client.walk(UCD_DSK_PATH, max_items=256))
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disk_percent = _indexed_values(client.walk(UCD_DSK_PERCENT, max_items=256))
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for index in sorted(disk_paths):
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path = _string_value(disk_paths.get(index))
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if not path or _int_value(disk_percent.get(index)) is None:
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continue
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items.append(
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DiscoveredSnmpHealthItem(
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item_id=f"linux.disk.{index}",
|
|
item_type="linux_disk_usage",
|
|
group="Storage",
|
|
label=_storage_usage_label(path),
|
|
unit="%",
|
|
)
|
|
)
|
|
|
|
return _deduplicate_items(items)
|
|
|
|
|
|
def _discover_sensor_items(client: "SnmpV2Client") -> list[DiscoveredSnmpHealthItem]:
|
|
sensor_types = _indexed_values(client.walk(ENT_PHY_SENSOR_TYPE, max_items=256))
|
|
sensor_values = _indexed_values(client.walk(ENT_PHY_SENSOR_VALUE, max_items=256))
|
|
sensor_names = _indexed_values(client.walk(ENT_PHYSICAL_NAME, max_items=256))
|
|
sensor_descriptions = _indexed_values(client.walk(ENT_PHYSICAL_DESCR, max_items=256))
|
|
|
|
items: list[DiscoveredSnmpHealthItem] = []
|
|
for index in sorted(sensor_types):
|
|
sensor_type = _int_value(sensor_types.get(index))
|
|
if sensor_type not in SENSOR_TYPE_LABELS or _int_value(sensor_values.get(index)) is None:
|
|
continue
|
|
kind, unit = SENSOR_TYPE_LABELS[sensor_type]
|
|
name = _string_value(sensor_names.get(index)) or _string_value(sensor_descriptions.get(index))
|
|
label = kind if not name else f"{kind} {name}"
|
|
items.append(
|
|
DiscoveredSnmpHealthItem(
|
|
item_id=f"sensor.{index}.value",
|
|
item_type="sensor_value",
|
|
group="Environmental",
|
|
label=label,
|
|
unit=unit,
|
|
)
|
|
)
|
|
return items
|
|
|
|
|
|
def _storage_usage_label(description: str) -> str:
|
|
normalized = description.strip()
|
|
if normalized in {"/", "/boot", "/home", "/var"}:
|
|
return f"Disk {normalized} usage"
|
|
if "disk" not in normalized.lower() and normalized.startswith("/"):
|
|
return f"Disk {normalized} usage"
|
|
return f"{normalized} usage"
|
|
|
|
|
|
def _is_monitorable_storage_path(description: str) -> bool:
|
|
normalized = description.strip()
|
|
if not normalized.startswith("/"):
|
|
return True
|
|
ignored_exact = {"/dev", "/dev/shm", "/proc", "/run", "/sys", "/tmp"}
|
|
ignored_prefixes = (
|
|
"/dev/",
|
|
"/proc/",
|
|
"/run/",
|
|
"/sys/",
|
|
)
|
|
return normalized not in ignored_exact and not normalized.startswith(ignored_prefixes)
|
|
|
|
|
|
def _deduplicate_items(items: list[DiscoveredSnmpHealthItem]) -> list[DiscoveredSnmpHealthItem]:
|
|
seen: set[tuple[str, str]] = set()
|
|
deduplicated: list[DiscoveredSnmpHealthItem] = []
|
|
for item in items:
|
|
key = (item.item_type, item.label)
|
|
if key in seen:
|
|
continue
|
|
seen.add(key)
|
|
deduplicated.append(item)
|
|
return deduplicated
|
|
|
|
|
|
def _indexed_values(values: dict[tuple[int, ...], Any]) -> dict[int, Any]:
|
|
indexed: dict[int, Any] = {}
|
|
for oid, value in values.items():
|
|
if oid:
|
|
indexed[oid[-1]] = value
|
|
return indexed
|
|
|
|
|
|
def _string_value(value: Any) -> str | None:
|
|
if value is None:
|
|
return None
|
|
if isinstance(value, bytes):
|
|
return value.decode("utf-8", errors="replace")
|
|
return str(value)
|
|
|
|
|
|
def _int_value(value: Any) -> int | None:
|
|
if isinstance(value, int):
|
|
return value
|
|
return None
|
|
|
|
|
|
def _status_label(value: Any) -> str | None:
|
|
if not isinstance(value, int):
|
|
return None
|
|
return STATUS_LABELS.get(value, f"status {value}")
|
|
|
|
|
|
def _timeticks_to_seconds(value: Any) -> int | None:
|
|
if not isinstance(value, int):
|
|
return None
|
|
return int(value / 100)
|
|
|
|
|
|
class SnmpV2Client:
|
|
def __init__(self, host: str, credential: SnmpCredential) -> None:
|
|
self.host = host
|
|
self.credential = credential
|
|
|
|
def get_many(self, oids: list[tuple[int, ...]]) -> dict[tuple[int, ...], Any]:
|
|
return dict(self._request(0xA0, oids))
|
|
|
|
def walk(self, base_oid: tuple[int, ...], max_items: int = 128) -> dict[tuple[int, ...], Any]:
|
|
values: dict[tuple[int, ...], Any] = {}
|
|
next_oid = base_oid
|
|
for _ in range(max_items):
|
|
response = self._request(0xA1, [next_oid])
|
|
if not response:
|
|
break
|
|
returned_oid, value = response[0]
|
|
if not _oid_starts_with(returned_oid, base_oid):
|
|
break
|
|
values[returned_oid] = value
|
|
next_oid = returned_oid
|
|
return values
|
|
|
|
def _request(self, pdu_tag: int, oids: list[tuple[int, ...]]) -> list[tuple[tuple[int, ...], Any]]:
|
|
request_id = random.randint(1, 2_147_483_647)
|
|
packet = _encode_message(pdu_tag, request_id, self.credential.community, oids)
|
|
last_error: OSError | None = None
|
|
for _ in range(self.credential.retries + 1):
|
|
try:
|
|
with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as sock:
|
|
sock.settimeout(self.credential.timeout_seconds)
|
|
sock.sendto(packet, (self.host, self.credential.port))
|
|
response, _ = sock.recvfrom(65535)
|
|
return _decode_response(response, request_id)
|
|
except OSError as exc:
|
|
last_error = exc
|
|
raise SnmpDiscoveryError(f"SNMP request failed for {self.host}") from last_error
|
|
|
|
|
|
def _oid_starts_with(oid: tuple[int, ...], base_oid: tuple[int, ...]) -> bool:
|
|
return oid[: len(base_oid)] == base_oid
|
|
|
|
|
|
def _encode_message(pdu_tag: int, request_id: int, community: str, oids: list[tuple[int, ...]]) -> bytes:
|
|
varbinds = b"".join(_sequence(_encode_oid(oid) + _tlv(0x05, b"")) for oid in oids)
|
|
pdu = _tlv(
|
|
pdu_tag,
|
|
_encode_integer(request_id)
|
|
+ _encode_integer(0)
|
|
+ _encode_integer(0)
|
|
+ _sequence(varbinds),
|
|
)
|
|
return _sequence(_encode_integer(1) + _tlv(0x04, community.encode("utf-8")) + pdu)
|
|
|
|
|
|
def _sequence(value: bytes) -> bytes:
|
|
return _tlv(0x30, value)
|
|
|
|
|
|
def _tlv(tag: int, value: bytes) -> bytes:
|
|
return bytes([tag]) + _encode_length(len(value)) + value
|
|
|
|
|
|
def _encode_length(length: int) -> bytes:
|
|
if length < 128:
|
|
return bytes([length])
|
|
encoded = length.to_bytes((length.bit_length() + 7) // 8, "big")
|
|
return bytes([0x80 | len(encoded)]) + encoded
|
|
|
|
|
|
def _encode_integer(value: int) -> bytes:
|
|
if value == 0:
|
|
return _tlv(0x02, b"\x00")
|
|
encoded = value.to_bytes((value.bit_length() + 7) // 8, "big")
|
|
if encoded[0] & 0x80:
|
|
encoded = b"\x00" + encoded
|
|
return _tlv(0x02, encoded)
|
|
|
|
|
|
def _encode_oid(oid: tuple[int, ...]) -> bytes:
|
|
if len(oid) < 2:
|
|
raise ValueError("OID must have at least two parts")
|
|
body = bytes([oid[0] * 40 + oid[1]])
|
|
for part in oid[2:]:
|
|
body += _encode_base128(part)
|
|
return _tlv(0x06, body)
|
|
|
|
|
|
def _encode_base128(value: int) -> bytes:
|
|
chunks = [value & 0x7F]
|
|
value >>= 7
|
|
while value:
|
|
chunks.insert(0, 0x80 | (value & 0x7F))
|
|
value >>= 7
|
|
return bytes(chunks)
|
|
|
|
|
|
def _decode_response(data: bytes, expected_request_id: int) -> list[tuple[tuple[int, ...], Any]]:
|
|
tag, message_value, _ = _read_tlv(data, 0)
|
|
if tag != 0x30:
|
|
raise SnmpDiscoveryError("SNMP response was not a sequence")
|
|
|
|
offset = 0
|
|
_, _, offset = _read_tlv(message_value, offset)
|
|
_, _, offset = _read_tlv(message_value, offset)
|
|
pdu_tag, pdu_value, offset = _read_tlv(message_value, offset)
|
|
if pdu_tag != 0xA2:
|
|
raise SnmpDiscoveryError("SNMP response was not a GetResponse")
|
|
|
|
pdu_offset = 0
|
|
_, request_id_value, pdu_offset = _read_tlv(pdu_value, pdu_offset)
|
|
if _decode_integer(request_id_value) != expected_request_id:
|
|
raise SnmpDiscoveryError("SNMP response request id did not match")
|
|
_, error_status_value, pdu_offset = _read_tlv(pdu_value, pdu_offset)
|
|
error_status = _decode_integer(error_status_value)
|
|
_, _, pdu_offset = _read_tlv(pdu_value, pdu_offset)
|
|
if error_status:
|
|
raise SnmpDiscoveryError(f"SNMP agent returned error status {error_status}")
|
|
varbind_list_tag, varbind_list_value, _ = _read_tlv(pdu_value, pdu_offset)
|
|
if varbind_list_tag != 0x30:
|
|
raise SnmpDiscoveryError("SNMP response did not include a varbind list")
|
|
|
|
responses: list[tuple[tuple[int, ...], Any]] = []
|
|
varbind_offset = 0
|
|
while varbind_offset < len(varbind_list_value):
|
|
varbind_tag, varbind_value, varbind_offset = _read_tlv(varbind_list_value, varbind_offset)
|
|
if varbind_tag != 0x30:
|
|
raise SnmpDiscoveryError("SNMP response included an invalid varbind")
|
|
oid_tag, oid_value, value_offset = _read_tlv(varbind_value, 0)
|
|
if oid_tag != 0x06:
|
|
raise SnmpDiscoveryError("SNMP varbind did not include an object identifier")
|
|
value_tag, value_value, _ = _read_tlv(varbind_value, value_offset)
|
|
responses.append((_decode_oid(oid_value), _decode_value(value_tag, value_value)))
|
|
return responses
|
|
|
|
|
|
def _read_tlv(data: bytes, offset: int) -> tuple[int, bytes, int]:
|
|
if offset >= len(data):
|
|
raise SnmpDiscoveryError("SNMP response ended unexpectedly")
|
|
tag = data[offset]
|
|
length, offset = _read_length(data, offset + 1)
|
|
end = offset + length
|
|
if end > len(data):
|
|
raise SnmpDiscoveryError("SNMP response length exceeded available data")
|
|
return tag, data[offset:end], end
|
|
|
|
|
|
def _read_length(data: bytes, offset: int) -> tuple[int, int]:
|
|
first = data[offset]
|
|
offset += 1
|
|
if first < 128:
|
|
return first, offset
|
|
byte_count = first & 0x7F
|
|
if byte_count == 0:
|
|
raise SnmpDiscoveryError("SNMP response used indefinite length")
|
|
return int.from_bytes(data[offset : offset + byte_count], "big"), offset + byte_count
|
|
|
|
|
|
def _decode_integer(value: bytes) -> int:
|
|
if not value:
|
|
return 0
|
|
return int.from_bytes(value, "big", signed=bool(value[0] & 0x80))
|
|
|
|
|
|
def _decode_oid(value: bytes) -> tuple[int, ...]:
|
|
if not value:
|
|
raise SnmpDiscoveryError("SNMP response included an empty object identifier")
|
|
oid = [value[0] // 40, value[0] % 40]
|
|
number = 0
|
|
for byte in value[1:]:
|
|
number = (number << 7) | (byte & 0x7F)
|
|
if not byte & 0x80:
|
|
oid.append(number)
|
|
number = 0
|
|
return tuple(oid)
|
|
|
|
|
|
def _decode_value(tag: int, value: bytes) -> Any:
|
|
if tag == 0x02:
|
|
return _decode_integer(value)
|
|
if tag in {0x41, 0x42, 0x43, 0x46}:
|
|
return int.from_bytes(value, "big")
|
|
if tag == 0x04:
|
|
return value.decode("utf-8", errors="replace")
|
|
if tag == 0x06:
|
|
return ".".join(str(part) for part in _decode_oid(value))
|
|
if tag in {0x05, 0x80, 0x81, 0x82}:
|
|
return None
|
|
return value
|